Histological and Immunological Description of the Leishmanin Skin Test in Ibizan Hounds.

The leishmanin skin test (LST), a delayed-type hypersensitivity (DTH) reaction to Leishmania infantum, can specifically identify dogs that have made a cell-mediated immune response to L. infantum infection. The Ibizan hound appears to be more resistant to L. infantum infection than other breeds of dog. The aim of this study was to describe the histological and immunohistochemical changes induced by the LST in Ibizan hounds living in an area highly endemic for leishmaniosis. The majority of dogs were apparently healthy, lacked serum antibody to L. infantum and blood parasitaemia, but had marked specific interferon gamma production after in-vitro blood stimulation with L. infantum. Leishmanin (3 × 108 killed promastigotes of L. infantum/ml) was injected intradermally and biopsy samples were obtained from a positive reaction at 72 h from nine Ibizan hounds. A moderate to intense, perivascular to interstitial dermatitis and panniculitis characterized the inflammatory response at the injection site. In addition, three samples had diffuse inflammation in the deep dermis and panniculus. Oedema and necrosis were present in the deep dermis and panniculus. Congestion and haemorrhage were observed in five biopsies. T lymphocytes (CD3+) and large mononuclear cells (lysozyme-) were the most prevalent cells. CD3+ cells were significantly more numerous than CD20+ B cells and lysozyme+ cells. B cells were sparsely distributed, especially in the deep dermis and panniculus. Rare neutrophils and macrophages (lysozyme+) were observed with few eosinophils. Toll-like receptor (TLR)-2 protein was expressed in large mononuclear cells mainly located in the superficial dermis. Leishmania immunohistochemistry was negative and quantitative polymerase chain reaction was positive in all cases. The intradermal injection of killed L. infantum promastigotes in Ibizan hounds causes similar histological and immunohistochemical findings to those described for human subjects and are indicative of a DTH response. Moreover, TLR2 protein is expressed in inflammatory cells similar to findings in clinically affected skin biopsy samples.

Clinicopathological findings in sick dogs naturally infected with Leishmania infantum: Comparison of five different clinical classification systems.

A wide spectrum of clinical and clinicopathological findings in dogs with canine leishmaniosis (CanL) due to Leishmania infantum exists. However, the majority of clinical descriptions have been published a long time ago and recent studies in Europe are almost lacking. In addition, clinical classification of sick dogs is not well-standardized, with different classification systems used by clinical and epidemiological studies, making comparison of studies a difficult task. The aims of the study were to describe the clinicopathological findings of dogs naturally infected with L. infantum at the time of diagnosis and to review and compare the various clinical classification systems for CanL available in the literature. Eighty-one healthy dogs and fifty-one dogs with CanL were studied and clinical and clinicopathological data were recorded. The most common clinical findings at diagnosis were skin lesions (78.4%), lymphadenomegaly (64.7%) and weight loss (47.1%). The most frequent clinicopathological abnormalities included mild to moderate non-regenerative anemia (62.7%), lymphopenia (25.5%), hyperproteinemia (52.9%) dysproteinemia (78.4%). and proteinuria (47.8%). Renal azotemia was rare (5.9%). Only 5.9% of the patients studied were classified in similar categories (mild, moderate and severe disease) when five clinical classifications systems were compared, while 11.8% of cases were classified in similar categories when only two clinical classification systems were considered based on the fact that they included therapeutic and prognosis recommendations. In conclusion, anemia and protein-related alterations are common in dogs with CanL. In contrast, renal azotemia is infrequent despite the high percentage of diseased dogs with proteinuria, indicating kidney involvement. Adequate clinical staging system is desirable in order to establish proper management, treatment and prognosis in dogs with CanL and to facilitate the comparison of clinical and epidemiological studies.

Dermatophagoides farinae-specific immunotherapy in atopic dogs with hypersensitivity to multiple allergens: a randomised, double blind, placebo-controlled study.

A randomised, placebo-controlled, double blind study was conducted on 25 dogs that had atopic dermatitis, together with skin test reactivity and elevated serum IgE to Dermatophagoides farinae (Df) and at least one additional allergen. Dogs were treated with either a Df-restricted immunotherapy solution (n=14) or a placebo (n=11) and evaluated 6 weeks and 3, 5, 7 and 9 months after the initiation of treatment using a clinical scoring system (SASSAD) and pruritus analogue scale scores. The Df-restricted solution and the placebo had an equal effect on both pruritus and the skin manifestations (P>0.05). The results of this study indicate that in dogs with atopic dermatitis based on hypersensitivity to environmental allergens in addition to D. farinae, Df-restricted immunotherapy is insufficient to control the disease. Consequently, a solution for allergen-specific immunotherapy should remain customised.

Traction alopecia with vasculitis in an Old English sheepdog.

A seven-year-old entire male Old English sheepdog was presented with a well circumscribed, completely alopecic area on the top of its head, located where a rubber band had been used for several years. A punch biopsy was taken from the centre of the lesion and histological examination revealed cell-poor, interface mural folliculitis with follicular atrophy and vasculitis. A diagnosis of traction alopecia was made. Oral pentoxyfilline, at 400 mg twice daily, was prescribed for two months, with a slight improvement. To the authors' knowledge, this is the first report of canine traction alopecia accompanied by vascular damage. This vascular damage may represent the pathomechanism of this type of alopecia in the dog.

Assessment of proliferative activity of canine dermal mast cells by bromodeoxyuridine and proliferating cell nuclear antigen labelling.

Cutaneous mast cells from skin biopsies of three healthy dogs and three dogs with atopic dermatitis were assessed for their proliferative potential using bromodeoxyuridine and proliferating cell nuclear antigen labelling. Mast cells isolated from the skin of two healthy dogs were also studied using bromodeoxyuridine labelling. Mast cells in skin biopsy specimens and mast cells isolated from the skin of healthy dogs did not incorporate bromodeoxyuridine. Two mast cells expressing proliferating cell nuclear antigen were seen around two superficial vessels in the dermis of one atopic dog. Epidermal cells, glandular epithelial cells, fibroblasts and endothelial cells incorporated bromodeoxyuridine and showed positive staining for proliferating cell nuclear antigen. These results suggest that canine mature mast cells do not proliferate in the dermis.